[clang] Do not crash when CXXRecordDecl has a non-CXXRecordDecl base.

[adamcz]

Summary

This can happen on some invalid code, like the included test case.

[hokein]

Thanks!

clang/lib/Sema/SemaDeclCXX.cpp

if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
     if (Dtor && Dtor->isUsed())
       VisitVirtualBases = false;
   }
 
   llvm::SmallPtrSet<const RecordType *, 8> DirectVirtualBases;
 
   // Bases.
   for (const auto &Base : ClassDecl->bases()) {
-    // Bases are always records in a well-formed non-dependent class.
     const RecordType *RT = Base.getType()->getAs<RecordType>();
+    if (!RT)
+      continue;
 
     // Remember direct virtual bases.
     if (Base.isVirtual()) {
       if (!VisitVirtualBases)
         continue;
       DirectVirtualBases.insert(RT);
     }
 

clang/test/SemaTemplate/temp_class_spec.cpp

namespace PR6181 {
   class s;
   
   template <class U>
   class a<s> // expected-error{{partial specialization of 'a' does not use any of its template parameters}}
   {
   };
   
 }
+
+// Check that we do not crash on invalid code that leads to invalid base.
+namespace {
+template <typename X>
+class Foo {};
+
+template <int Y>
+class Bar;
+
+template <typename Z>
+class Bar<0> : public Foo<Z> { // expected-error{{partial specialization of 'Bar' does not use any of its template parameters}}
+  Bar() : Foo<Z>() {}
+};
+} // namespace